From the moment I first saw Isaacs as Evil English Arch-Baddie #1 in The Patriot, getting bayonetted in the neck by the Mel Gibson, I knew he'd be a perfect addition to the Empire. It only took 14 years to happen, but after proving himself as Captain Hook and Lucius Malfoy, the most killer Jason not named Voorhees couldn't be denied any longer.
Entertainment Weekly debuted his intro video, which confirms both that he's not officially a Sith and that he's a Pau'an. I also like this particular quote from Lucasfilm's Pablo Hidalgo: "This isn't like cartoons I grew up with in the '80s where you'd have the villain lose every week and yet every week we'd have to believe he's some sort of threat."
Given that we know the Empire's still in control when the series ends, I should hope not. Although Hordak acted the fool in cartoons and still somehow held on to power.